Plaster of paris casts have been used to immobilize body members for some time. These bandages are made by depositing plaster of paris on a reinforcing scrim material such as gauze. When the plaster of paris is dipped in water, reactions take place which result in the hardening of the cast material. Plaster of paris casts, however, suffer from a number of disadvantages. X-ray transmission through the cast to determine whether a fracture has properly set is extremely difficult. In addition, the cast is quite heavy and restricts the mobility of patients wearing the east.
In order to overcome the disadvantages of plaster of paris casts, numerous attempts have been made to develop plastic or plastic reinforced materials as replacements for plaster of paris. U.S. Pat. Nos. 3,241,501 and 3,881,473 disclose casts which are made with a flexible fabric impregnated with a polymer which is capable of being cured by ultraviolet light.
Other attempts to replace plaster of paris casts are disclosed in German Offenlegenschrift numbers 2353212 and 2357931, U.K. Patent #1,578,895, and PCT Application #WO 81/00671. These bandages are open weave fabrics coated with polyurethane prepolymers, that is, reaction products of isocyanates and polyols. The bandages are dipped into water in the same manner as the plaster of paris and then applied to the limb of the patient. The water causes the prepolymer to polymerize and form a rigid polymer structure.
More recently it has been found that in working with such materials having a prepolymer resin coating that the tackiness of the resin of the bandage can make working with the bandages difficult and cumbersome for the doctor. In an attempt to address this issue a glove lubricant comprised of water, sorbitol, mineral oil and silicon fluid has been sold by 3M Company, St. Paul, Minn., under the trade name CastCreme with instructions to apply the lubricant to the gloves of one applying an isocyanate-functional prepolymer coated cast after wrapping of the cast but before molding of the cast to avoid having the exposed casting material adhere to the gloves of the one applying the cast. This is disclosed in the background of U.S. Pat. Nos. 4,667,661 and 4,774,937.
The '661 and '937 patents are directed to addressing the adherence issue by providing the resin itself with a lubricant. The curable resin coated sheet is prelubricated with a lubricant which is either a) bonded to the resin, b) added to the resin or applied to the surface of the coated sheet or c) provided in a combination of the bonding and surface application described. In many instances however, the tacky feature of the orthopaedic bandage is desirable. As by way of example when the applier is attempting to get the end of the bandage to stick to the surface of the bandage wrap in order to terminate the application of the bandage. The addition of lubricant in the resin permits relative slipping of the resin coated sheet and requires molding the cast in position and holding it in position to prevent slippage.
Coatings for substrates having a low coefficient of friction have been shown in U.S. Pat. No. 4,100,309 entitled "Coated Substrate Having a Low Coefficient of Friction Hydrophilic Coating and a Method of Making the Same". That reference describes a substrate which is coated with a polyvinyl pyrollidone-polyurethane inter polymer. In the method, a poly-isocyanate and a polyurethane in a solvent such as methyl ethyl ketone are applied to a substrate and the solvent evaporated. If the substrate is a polyurethane, only the polyisocyanate need be employed. Polyvinyl pyrollidone in a solvent is then applied to the treated substrate and the solvent evaporated. The substance and coated objects described in this reference are used in blood and body contacting environments. In order to lubricate the introduction of devices into openings in the body.